NOTE  The wording of the Regulation in the case of EPA
includes ..or other means to plot electronically the
range and bearing of targets to determine collision risk.
Therefore manual plotting equipment is no longer acceptable
except for existing vessels still complying with SOLAS V/74.

Automatic
Radar Plotting Aid (ARPA)
ARPA equipment provides for manual or automatic acquisition
of targets and the automatic tracking and display of all relevant
target information for at least 20 targets for anti-collision
decision making. It also enables trial manoeuvres to be executed.

CARRIAGE
REQUIREMENTS

9
GHz ("X" Band) Radar - is required on any vessel
of 300 gt. and over. "X" Band radars can locate radar
transponders including search and rescue transponders (SARTS).
3 GHz ("S" Band) Radar - to- be fitted as the
second radar, which is required on ships of 3000 gt. and over
unless the Administration considers it appropriate to carry
a second 9 GHz Radar. The two radars must be functionally independent
of each other. The MCA will require a reasoned case for why
a 3 GHz radar cannot be carried. "S" Band radars will
not detect SARTS or other radar transponders.

EPA - To be incorporated in Radar equipment on ships
of 300 gt. and over, but less than 500 gt

ATA - To be incorporated in Radar equipment on ships
of 500 gt. and over (replacing the requirement for an EPA)
On ships of 3000 gt. and over the second radar must also be
equipped with an ATA. The two ATAs must be functionally independent
of each other.

ARPA - To be incorporated in one radar equipment on ships
of 10000 gt. and over. The second unit must incorporate ATA
if not ARPA.

Summary
of minimum Radar requirements:

GROSS
TONNAGE

9GHz
RADAR

3GHz
RADAR*

EPA

ATA

ARPA

300
 499

1

.

1

.

.

500
 2999

1

.

.

1

.

3000
 10000

1

1

.

2

.

10000
+

1

1

.

1**

1

*
Administration may approve a second 9 GHz radar instead
** Or second ARPA